Basis of Presentation and Recently Issued Accounting Pronouncements (Details) $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net change in net cash used in investing activities			$ (71,402)	$ 256,683
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net change in net cash used in investing activities				4,092
Restricted cash						$ 6,650
Distributions in excess of accumulated net income | Accounting Standards Update 2017-05
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings					$ 12,756
Distributions in excess of accumulated net income | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease asset			3,000
Lease liability			$ 3,000
Distributions in excess of accumulated net income | Accounting Standards Update 2016-02 | Discount Rate
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fair value inputs, discount rate (percent)			0.044
Restatement Adjustment | Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net change in net cash used in investing activities				(6,650)
Restatement Adjustment | Accounting Standards Update 2017-05
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings					12,756
Restatement Adjustment | General and Administrative Expense
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of non-recoverable payroll		$ (1,019)		(2,846)
Restatement Adjustment | Property Operating Expense
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of non-recoverable payroll		$ 912		$ 1,827
Restatement Adjustment | Distributions in excess of accumulated net income | Accounting Standards Update 2017-05
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings	[1]				$ 12,756

[1] See Note 2. Recently Issued Accounting Pronouncements Adopted.